(1) Field of the Invention
The present invention relates to a method of manufacturing heat exchange elements for exchanging heat between two or more fluid flows and, more particularly, to a method of manufacturing block-type heat exchange elements.
The term heat exchange as used herein is intended to include not only the exchange of sensible heat between two or more fluid flows but also the exchange of latent heat in the form of moisture.
(2) Description of the Prior Art
Known in the prior art are laminated type heat exchange elements wherein flat and corrugated sheets are alternately disposed one upon the other in such a manner as to form two sets of fluid channels intersecting each other (see, for example, Japanese Examined Utility Model Publication No. 50-22365). This type of heat exchange elements are difficult to assemble and expensive to manufacture because the flat and corrugated sheets must be bonded together by a sequence of complicated procedures. Furthermore, the sheet materials must be sufficiently stiff and self-sustaining to facilitate their handling, bonding or welding operations. Thus, there is a limitation on the minimization or reduction that can be made to the wall thickness of the sheet materials, thereby precluding any enlargement of the heat transfer surface per unit volume of the element and, hence, any increase in the heat exchange efficiency.
Also known in the prior art are the block type heat exchange elements comprising monolithic blocks of a single material such as graphite. The graphite block is machined to form two or more series of fluid channels for circulating heat exchange fluids. However, the disadvantages of machining lie in the high production costs entailed and in the unsatisfactory limitations placed on the allowable minimum thickness of the wall located between adjacent channels.